Method of producing stereotype printing forms electrolytically



June 10 1941- w. HUGENTOBLER METHOD OF PHODUCING STEREOTYPE PRINTING FORMS ELECTROLYTICALLY Filed Dec. 21, 1937 lill 2 Sheets-Sheet 1 Patented June ai? p STATES inurl-:1yrv OFFICE ME'rnon or PnonUclNG s'rnnno'rrrn rmNTING FonM-s Emc'rnoLmcALLY Walter Hugentobler, St. Gallen, Switzerland, assignor to Spectraldruck G. m. lull., St. Gallen, 'Switzerand, a `Swiss company ApplicationV December 21, 1937, Serial No. 181,051 In Switzerland December 23, 1936 5 Claims.'

' tion of stereotype plates, and o'n the conventional mode of applying coats of lacquer to printing surfaces. The method according to the invention comprises applying to a non-porous iron carrier, which has previously been accurately planed by. grinding, a layer of corrosion-proof electrolytically lling in the blank portions with y a layer of stereotype metal up to the' level of the coat of resist, removing the coat of resist.

by rinsing, so that in its place a surface is formed which is set :back from the surface of the printing image and follows the outlines of the latter and rendering one of said surfac color-receptive and the other color-repellent.

This method thus distinguishes fundamentally from all the methods which have hitherto been used for making stereotype plates and according to which the printing image was produce. on the plate by etching and the blank surface portions were treated with fatfrepellent preparations, the present method having appreciable advantages.

I'he reproduction of the image contrasts sharply even at the finest details thereof irrespective of Whether fiat or cylindricalprinting forms are used, and particularly, a screen pattern can b`e reproduced true to the original uniformly throughout, contrary to the screen produced pictures, which have hitherto been obtained by means of an etching method, by means of which it is impossible to obtain an entirely uniform reproduction throughout, due to deficiencies unavoidably inherent .in hand-Work, so that nonuniform portions `arise in the-printing image. Therefore, a perfect' reproduction of the image is obtained, according to the invention, even if the finest screen is used.

Furthermore, such stereotype printing forms are applicable with particular advantage for the printing in rotary printing presses, for which purpose it is, as is Well known, required that the diameter of the printing cylinders must remain accurately true to size, in that, if a stereotype printing surface is to be taken down, the electrolytically applied metal portions can be removed by simply reversing the poles of the bath to the effect that the 'circumference of the cylinder remains intact and the cylinders can be put to another use unaltered. It is obvious that plane printing forms can Ibe used over and over again as well as cylindrical forms by removingthe image electrolytically, after the printing surface has been freed from color residues byV means of a solvent, so that removing the image I by means of an abrasive or b y grinding, for the purpose of using the form carrier again, can -be dispensed with.

Moreover, in carrying out the method accord- -ing to the invention'not only the thickness of the layers applied, that is the height of relief of the image, can be varied, at will; by appropriately varying the factors determining,- the operation of the electrolytic bath, but the image is formed so as to produce the nest printing effects entirely automatically.' In contradistinction thereto, in. applying etching methods for producing high relief effects, it is often necessary to cover the nerdetails o'f the printing image after the initial etching, in orderl to be, able to corrode other portions to still .greater depths, which requires complicated ,andthus expensive operations, as against the method according to the invention which can' be carried into effect in a simple and thus-economical manner with the result that a highly durable stereotype printing form unsusceptible to exterior iniiuences is obtained. v

Again, the resistivity of the stereotype printing form against fatty acids, which are principally used in connection with the printing colors employed for this purpose, can be increased by electrolytically applyinga thin 'layer of chromium to the blank surface portions.

Some specic modes of procedure for carrying the method according to the invention into eiect Y for producing stereotype printing forms are hereinafter described by way of example only and by having reference tothe accompanying drawings-in which the various working phases are illustrated by a number of larger scale schematicsections of a stereotype .printing form. I

In the accompanying drawings Figure 1. is va side sectional view of an iron plate which fornisthe foundation of the printing form. v

Fig. 2 is a. view similar to Fig. 1 with an'A elec trolytic plating of non-rusting and non-corrosive metal applied to its upper surface.

. 6 is a view similar .to 5 with the image surfaces, leaving the resist applied to the print,

ing surfaces.

Fig. 9 is a view simusr to Fig. s but with an.

electrolytic plating of zinc applied to the nonprinting surfaces up to the level of thc. resist on the printing surfaces.

Fig. 10 is a view similar to Fig. 9 but showing a thin electrolytic plating of chromium applied to the zinc surfaces. .I

Fig. 11 is a view similar to Fig. 10 with the resist removed from the printing surfaces.

' Fig. 12 is a view similar to Fig. 11` but with a coating of Syrian asphalt applied to the printing surfaces.

Fig. 13 is a view similar to Fig. 12 of the finished printing form with printing color applied to the image surfaces.

A first specific mode of procedure for carrying into eect the method of producing a flat stereotype printing form, according to the invention, consists in the following: i

As a carrier an iron plate i is used which must be entirely devoid of porous portions and the surface of which is ground plane. 'I'his plate is plated electrolytically with a layer 2 of rust and corrosion resisting metal in order to facilitate the subsequent application of a layer of stereotype metal, that is, metals which are used for making stereotype plates, and are deposited electrolytically, for instance copper, zinc, lead, brass, antimony, nickel and chromium.

Two principal' .kinds of stereotype printing surfaces can be produced, namely, a printing surface the basic material of which consists of zinc and one the basic material of which consists of copper, these printing surfaces being provided with a covering layer.of antlmony, lead or the like.

For producing the stereotype printing surface the basic material of which consists of zinc, the plating 2 of nickel (Fig. 2) is at first coated with a thin layer of copper to which a covering layer 3 of zinc is then applied electrolytically (Fig. 3). The covering layer of zinc is prepared in a` manner as usual for receiving the reprint or the photographic reproduction of the image. After the application of the image 4 the surface portions adjoining the image portions of the st'ereotype printing form are thoroughly coated with gum 5, as in Fig. 5, and the image and its covering of gum are removed from the plate, as in Fig. 6, and the plate is then preliminarily slightly etched, if desired, andl then the printing form is washed' over with a resist consisting of .a solutioncf a mixtureof asphalt and Canadian balsam in rectified turpentine, as shown in Fig. 7,.

the coating of resist being indicated by a. The blank surface portions that are not to be printed, that is, the surface portions which adjoin the image portions and are not intended to be inked in during the printing operation are protected from this resist by the coat of gum, whereas the printing surface portions receive ythe resist and retain the same. The gum is then dissolved by steaming or by wiping hot water-.across the same, so that the layer of gum applied to the blank ing the gum coated portions is removed with the same. whereas the printing surface portions remain covered with a protecting coat of resist l for example, turpentine. which does not aect the in a water bath another layer 5 of zinc is applied' electrolytically (Fig. 9), the thickness of this layer being such that the layer is flush with the coat of resist 5a.

To this layer l of zinc a thin layer. I oi chromium is applied electrolytically (Fig. lil).

Then the printing form is taken out of the bath,

lcleanly washed and coated with gum once more,

whereupon the resist is washed of! with a solvent.

gum coat, so that at the bottom of the depressions corresponding to the image portions, the basic metal is laid bare (Fig. 11). Thereupon, the metal surface is rubbed down with oil of cloves and a solution of Syrian asphalt in rectified turpentine is applied so as to form a coat sticking to metal at the bottom of the depression (Fig. 12). After the gum coat is dissolved the coat 1 of Syrian asphalt which corresponds to the printing image sticks permanently to the depressions without, however, filling them out for the full height, the thickness of the coat being predetermined by correspondingly proportioning the asphalt mixture. Thereupon, the printing form is cleanly rinsed in order to free all the blank surfaces from asphalt residues which may have deposited on the gum coat. 'I'hen a further coat of gum arabic is applied and printing ink. that is, black lithographers ink rich in coloring substance and poor in fat content, is rolled into said coating of gum. 'I'he deposits of printing ink on the surface of the gum costare then removed by means of steam or hot water, so that only the printing ink adhering to the coat of Syrian asphalt in the image portions is left. Subsequently, the blank surface portions are etched with zinc etch in order tol prevent them from attracting color during the printing operation. A new coat of gum is then applied thereto. Then the plate is washed oi! again for removing the printing ink, the washing liquid consisting of turpentine, sothat the asphalt is removed from the depressions also.

As these operations are terminated a solution of the resist of asphalt and Canada balsam is applied to the gum coat once more so as to fili the depressions up to a certain height, whereupon the gum coat is removed, whereby the resist adhering to the gum above the blank surface portions is removed also. 'Ihen the surface of the j stereotype 'printing form is rinsed with water.

surface portions is dissolved and the resist coverslightly etched and rinsed once more, -whereupon the flat stereotype printing form is nt for use, as is indicated in Fig. 13, in which the printing color is indicated by I.

During the printing operation the printing color l fills the depressions above the color-receptive coat 1 of resist thus permitting to control the effect of the imprint, as desired, depending upon whether more or less ink is supplied into the depressions, it being even possible to provide an excess amount of ink. so that the ink rises above the edges of the depressions.

The treatment described abois-1s obviously carried out in the same manner when cylindrical stereotype printing forms are produced, with the sole exception that, while the fiat printing forms are treated in a tray, the treatment of thecylindrical printing forms is carried out in a trough or vat in which the cylinder is continuously turned.

The productionlof a stereotype printing form ythe basic material of which consists of copper is effected in the following manner:

The surface of the cylindrical printingform is at first nickel-plated as mentioned above, whereupon a relatively thick layer of copper is de-A posited electrolytically. Then the surface of the printing forml is carefully cleaned by rinsing and covered with a thin coat of gum arabic, -in order to prevent oxidation. Preparatory to applying the printing image to the printing form or producing it thereon the surface of the printing form is rinsed with water, in this case also, to which gether with the resist adhering thereto above the blank surface portions, by means of steam or hot water. Then the surface of the printing form is carefully cleaned once more byvrinsing with water. until all impurities had been removed from the blank surface portions. and is freed from any excess of, fatty substances by washing with a solution of potassium cyanide and c austic soda in water, and is then carefully cleaned by rinsing with water. Thereupon a layer of antimony or lead is applied electrolytically up to the top of the coat of resist, thus providing a smooth surface throughout the extent of the printing form. Then the printing form is again thoroughly rinsed and coated with gum arabic.

, Then the surface of the printing form is washed with rectied turpentine which does not v affect the gum coat, so that the resist is dissolved and the basic copper material is laid bare at the bottom of the depression. To the dry surface of the gum coat on the printing form a. coat of a. solution of asphalt resist in rectified turpentine is applied, so that a uniform surface is obtained. When this coat of resist has set. the printing form is washed with water, so that the gum coat and the overlying coat of asphalt are dissolved, whereas the printing surface portions of the image remain coveredby asphalt resist. After the blank surface portions have been completely freed from all residues of asphalt resist, thefsurface of the printing form whereas the printing surface portions are fatreceptive. Ihereupon the surface of the printing form is again coated with gum and the layers of asphalt resist and printing ink are -washed off with turpentine across the gum. After rinsing, the surface ofV theprinting form is etched once more with a diluted mixture/of sulfuric and nitric acid andthen the stereotype printing form is fit for use.

Especially in applying the mode of procedure llast-described even the production of inverted images could be effected in electrolytic manner.

To this end the iron core is provided with a nickel-plating in the manner described in connection with the preceding mode of procedure, but in distinction therefrom, a layer of antimony and lead or an alloy of these metals is applied;

After the application of the image to this layer,

the coat of asphalt resist is applied in the same.

manner as previously described and then a covering layer of copper is deposited electrolytically. The printing image is then constituted by the entire .printing surface of the printing form, whereas the remaining surface portions consisting of lead or antimony are not color-receptive and are therefore not printed, due to having been etched by means of sulfuric and nitric acid.

If such a stereotype printingform is not to Y he put to further use, the plate or cylinder is is again coated with gum arabic, whereupon and is then etched by means of a diluted mixture of sulfuric and nitric acid.l By this means the lead or antimony is made water-receptive,

cleaned from adhering color residues by means of benzine or turpentine and isthen immersed in an electrolytic degreasing bath for removing all the fatty substances without' resorting to mechanical treatments, such as grinding, or

abrading by means of emery or the like. To this 'a end the body of the printing form is immersed in the electrolytic bath in which the upper metal layer had been produced and is subjected to the action of the electrolyte for exactly the samelength of time as before, while the poles of the bath are reversed, so that the body of the printing form provides' the anpde, in.' consequence whereof the layer having previously been electrolytically applied, is removed again. in electrolytic manner. Then the fiat or circular printing form of accurately initial thichiess or circumferential length respectively is in condition for receiving a new image. In this way, on

the one hand, great savings in material are.V

made and, on the other hand, in applying the printing form to rotary printing presses, the advantage ensues that the circumference' of the printing cylinders remains unchanged at all times.

Relative to the hand etching methods involving the risk that the printing plates and more particularly the printing cylinders are easily damaged by bumping against other objects, the advantage accrues that in the method according to the invention the printing forms can be treated-without being damaged. This will be readily understood when it is observed that the plates used for making fiat printing forms can simply be transferred from one tray to the other by hand, while the cylindrical printing forms can be transferred from one vat to the other lof a series of collateral vats by means of a crane.

By means of the' method according to the invention the layer to be applied can be kept down to so small a thickness that it has no tendency to crack. This is of particular advantage, when it is intended to use the stereotype printing forms for offset printing in connection with which the printing forms are clamped to a cylinder. In putting cylindrical forms etched by a hand etching method n v7:is use, it has been experienced that portions nl the exterior layer dropped off after the material had been damaged, so that the bare metal underneath wascovered with printing color, in consequence of which, the edge of the printingy sheet became blurred. 'I'his drawback is.completely eliminated according to this invention. l

Furthermore, the method according to the invention is of particular advantage for the production of stereotype printing forms for rotary printing presses. since cylindrical printing forms having a circumferentlally continuous printing surface, can be produced by meansl of this method with ease.

By this means it would be possible to printi endless pictures on webs of materials, such as paper, textile fabrics, aluminum foil, etc., in a continuous operation. I

For the printing of books such stereotype printing forms are applicable with advantage in cases where the printing form is inked in by means of a separate inking roller. In such an arrangement the printing form is effectively protected, due to the fact, that it is inked in by means of a roller made of gelatine. By including a rubber roller for transferring the color from the printing cylinder to the paper web it would be possible to print books in a manner similar to offset printing, by means of the invention.

The method according to the invention can be carried into effect in still other manner, as follows:

'able method and the surface of the stereotype printing form is degreased, particularly, at the surface portions which are not printed, that is,

at the blank surface portions of the printing form.

Then, a coat of nickel is deposited electrolytically up to the full height of the coat of resist present, whereupon the body of the printing form is carefully cleaned by rinsing it with water, coated once more with gum, and the layer of asphalt resist is removed, in a manner known per se, so that the basic copper or brass material is exposed in the depressions. The surface of the printing form is then washed with a solution of asphalt in rectiiied turpentine, this coat of asphalt forming at the bottom of the depressions a' color-receptive support the outlines of which are conform with those of the printing image. After printers ink has been rolled into the gum, the latter is removed together with the ink from the blank surface portions by means of steam or hot water, so that only the printing surface portions remain covered with ink. The metal is then etched by means of diluted sulphuric acid.

After the printing surface has been coated with gum once more the image is washed oil.' together with the ink, by means of turpentine, so that the metal of the basic material is exposed in the depressions again. Thereupon, the surface is washed over with a solution of asphalt without an addition of Canada balsam so that= above the copper or brass a color-receptive layer ls formed in the depressions, whereas the adjacent nickel surface portions are color-repellent, due to having been treated with sulphuric acid.

haar AVAILABLE corr changing the succession of operations, in such manner, that first a layer of nickel is deposited on the printing surface which layer is subjected to the treatment described and to' which the image ls applied, whereupon a second layer of copper or brass is electrolytically deposited. If then the etching is carried out in a similar manner, the entire surface of the printing form is rendered color-receptive with the exception of the depressions which are provided with bottoms of nickel, this metal being color-repellent owing to having been etched by means of sulphuric acid. I

`The method accordingto the invention is applicable for the production of printing forms for other kinds of printing than stereotype printing the image portionsof 'the plate, preliminarily etching the image portions, applying a resist comprising a solution of asphalt and Canada balsam which, by reason of the coating of guml is taken up only by the printing surfaces, then removing the coating of gum by steaming, whereby the asphalt and balsam remains adherent to the printing portions, electrolytically depositing a stereotype metal on the exposed part of the metallic surface of the plate up to the level of the resist surface, removing the resist from the printf ing portions by washing with a solvent therefor,

so as to form a surface corresponding in outline to the printed image depressed with respect to the plate surface, thereupon treating the elevated surfaces to cause them to repel color, and treating the depressed surfaces to enable them to attract color.

2. Process according to claim 1, in which the base of the plate is an iron plate and in which said base is rst electrolytically coated'with a non-corrosive metal, and a coating of'zinc is electrolytically deposited on said non-corrosive metal. I

3. Process according to claim 1 and in which a a thin layer of,chromium is electrolytically deposited on the stereotype metal coating which forms only the non-printing portions.

f4. Process according to claim 1, and wherein the resist coating which insulates the image por- WALTER HUGENTOBLER. 

